xyMonom.cc

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#include "xyMonom.h"
#include "parseTools.h"



using namespace std;


unsigned int xyExpPair::extractExplicitExponent(stringstream&  sstream)
{
        string res="";
        
        int num=0;
        int sign=getSign(sstream);

        if (sign<0)
        {
                throw "negative exponents not allowed fom monoms! " ;
        }

        sstream >> ws;
        sstream >>num;
        if (sstream.fail())
        {
                throw "no exponent given" ;
        }
        return num;
}





xyExpPair::xyExpPair(std::stringstream&  sstream)
{
        #ifdef DEBUG
                std::cerr << "create xyExpPair" << std::endl;
                std::cerr << "xyExpPair stream: =" << sstream.str() << std::endl;
        #endif

        assert (!sstream.fail());

        x_exp=0;
        y_exp=0;

        char a; 
        bool isXExp=false;
        bool isYExp=false;

        sstream >> ws;
        
        while (!sstream.eof() )
        {
                assert (!sstream.fail());
                a=sstream.peek();
                #ifdef DEBUG
                        std::cerr << "a " << a;
                #endif
                if (a=='*')
                {
                        isXExp=false;
                        isYExp=false;
                        sstream >>a;
                        sstream >> ws;
                        continue;
                }
                if (a=='x')
                {
                        x_exp=1; // der x-Exponent ist implizit  mindestens 1 , wenn kein '^' folgt
                        isXExp=true;
                        isYExp=false;
                        sstream >>a;
                        sstream >> ws;
                        continue;
                }
                else 
                if (a=='y')
                {

                        y_exp=1; // der y-Exponent ist implizit mindestens 1, wenn kein '^' folgt
                        isYExp=true;
                        isXExp=false;
                        sstream >>a;
                        sstream >> ws;
                        continue;
                }
                else
                if (a=='^')
                {
                        sstream >>a;
                        if (isXExp)     
                        {
                                x_exp=extractExplicitExponent(sstream);
                                //assert(x_exp!=0);  - kann auch 0 sein!
                        }
                        else if (isYExp)
                        {
                                y_exp=extractExplicitExponent(sstream);
                                //assert(y_exp!=0);
                        }
                        else throw "[xy]-polynom: unknown variable";
                        sstream >> ws;
                        continue;
                }
                else 
                {
                        sstream >> ws;
                        if (sstream.eof() || a=='-' || a =='+' )                
                                return;
                        else
                        {
                                throw "error during extracting (x,y) exponents";
                        }
                }
        }
}